In recent years, ongoing increase to capacity and speed is required in response to implementation of broad band to mobile communication services. As a result, third generation mobile communication systems such as W-CDMA (Wideband Code Division Multiple Access) or next-generation mobile communication systems in substitution for 3.5th generation mobile communication systems are being implemented globally. Assignment has commenced within Japan in relation to frequencies for 3.9th generation mobile communication systems that represent the mobile communication system for association with fourth generation mobile communication systems. LTE (Long Term Evolution) is a type of 3.9th generation mobile communication system that is considered to embody the most effective standard for association with fourth generation mobile communication systems.
In LTE, OFDMA (Orthogonal Frequency Division Multiplexing Access) is used in relation to downlink communication from a radio base station to a radio terminal. Furthermore, SC-FDMA (Single Carrier Frequency Division Multiple Access) is used in relation to uplink communication from a radio terminal to a radio base station. These multiplexing schemes realize multiplexing for users by allocation of two-dimensional radio resources embodied by frequency and time.
The downlink radio resources are divided into units termed resource blocks (RB). RB includes PDCCH (Physical Downlink Control CHannel) for transmission of downlink control information and PDSCH (Physical Downlink Shared CHannel) for transmission of downlink user data.